I think it's lovely that a startup can go from fruition to abject failure in 4 months. If you really don't believe in the product any more, that's that and you should be happy you got out so quickly.

That being said, 4 months isn't a lot of time although it sounds like you've spent considerable energy on this product. If the software works you might consider unwinding this business through a sale or a partnership. If what you need is sales, find a motivated sales person. I definitely agree with other posters that you could use a motivated marketing person as well; you might still be able to make a go of it.

When we were starting out we definitely fell victim to the custom request bug, but as you grow you'll realize that no client is worth upending your whole business.